UA82689C2 - Method for connection of steel head with polymer-composite body of pump rod - Google Patents

Abstract

Method for connection of steel head with polymer-composite body of pump rod includes filling of space between contacting surfaces with glue substance for provision of fixation. At that the end of the body of polymer-composite rod and opening of steel head are made stepped. On the last stage of the opening that has the smallest diameter one provides recess. To the opening of the head one installs insert with conical end with angle of conicity 100-120º for holding apart broomed to depth of recess and soaked with epoxy tar end of polymer-composite body of the rod, this is pressed to the head. Reliability and strength of the joint are increased.

Description

The invention relates to the oil and gas industry, namely the connection of a fiberglass rod with steel pump rod heads, which are used in rod pump installations for oil extraction from wells.

In domestic industry, as a rule, steel is used for the manufacture of pump rods. The experience of foreign companies that have used fiberglass pump rods in recent years shows a number of advantages of such rods over steel ones: increased corrosion resistance, reduced weight of the pump rod column, increased productivity, reduced maximum load on the polished rod, reduced minimum load, reduced torque and electricity consumption (Matveichuk A.T., Mykhaylov I.V. Reuse of fiberglass pump rods abroad // Obzor inform. Ser. Neftepromslovoe delo. -

M..!VNYOZNG, 1985. - 18p.). One of the disadvantages of fiberglass pump rods is the unreliable connection of the composite rod with steel heads.

A pump rod head design is known, which has a cylindrical part with a hole towards the middle of the head on one side and an external thread on the other side |US Patent Me4430018 cl. E16811/00 07.02.84 |

The opening of the cylindrical part consists of ring protrusions, which are formed by conical grooves between them. At the other end, the head also has a hole along the axis, which is connected to the hole of the cylindrical part. In the middle of this hole, the valve stem is placed, the head of which is located at the bottom of the cavity of the cylindrical part.

The cylindrical part is intended for fixing in it with the help of epoxy resin the polymer-composite rod of the pump rod. The outside of the valve hole has an internal thread in which a screw is threaded to connect to the end of the valve stem to transmit the longitudinal force through the valve to the end of the plastic rod.

For the proposed method of connecting a polymer-composite pump rod with a steel head, the closest design is (US Patent Мо4433933 кл. Е168011/00 02/28/84|), which consists of a steel head at the end of a plastic rod. The head works under the action of longitudinal tensile forces forces and consists of a cylindrical body lining the rod and a threaded end for connection with the coupling. The body of the head has a hole with spiral wedge-shaped grooves, the surface of which has a radial inclination at an angle in the direction of the longitudinal axis of the body of the head. The inner edge of the grooves corresponds to the outer the surface of the plastic rod.The grooves are filled with an adhesive substance that provides a fixed connection with the rod and a movable connection with the grooves.

The disadvantage of the above-described structures is the low strength of the adhesive connection. Only a small amount of fibers, which are on the surface of the body of the rod, participates in gluing. Operating experience and experimental studies in laboratory conditions have shown that when such a connection is destroyed, the outer fibers of the rod break, while the inner fibers remain intact, which is due to the specific structure of the polymer composite material, which consists of a connecting (epoxy resin) and reinforcing (unidirectional polymer fibers) phases.

During the operation of polymer-composite pump rods, steel heads are destroyed by corrosion, damaged by friction against the walls of pump-compressor pipes, and the threaded connection fails. While the plastic rods remain intact. There is a need to replace the steel heads with new ones.

The task that stood when creating this invention was to improve the method of connection, in which by involving the internal fibers of the polymer-composite body of the pump rod to redistribute the effect of tensile loads from the outer fibers to the middle and inner fibers. In addition, introduce an additional element that will withstand the main load from the action of longitudinal tensile forces, which will reduce the destructive effect of these forces on the adhesive joint and increase the reliability and strength of the connection of the polymer-composite body of the rod with the steel head. It is also necessary to ensure the possibility of replacing the fired steel heads.

The problem is solved by the fact that in the method of connecting the steel head to the polymer-composite body of the pump rod, which includes filling the space between the contacting surfaces with an adhesive substance to ensure fixed adhesion according to the invention, the end of the body of the polymer-composite rod and the opening of the steel head are made stepped. On the last stage with the smallest diameter of the socket of the steel head, a recess is used. A steel insert with a conical end with a taper angle of 100...1207 is placed in the hole to expand the end of the polymer-composite body of the rod, which has been expanded to its length and impregnated with epoxy glue, which is pressed into the head and crimped in several places together with the metal head with a three-stage jamming stamp and prevention of disconnection of the plastic rod under the action of longitudinal tensile loads.

The stepped surface of the contact between the steel head and the end of the polymer-composite body of the rod is made in order that when the polymer body of the rod pressed into the head is stretched, not only the external, but also the intermediate and internal fibers of the rod are involved and thus increase the pulling force of the pump rod. The first step on the side of the axial load should be longer than the others. The end of the last step is made conical for a certain length, so that when crimping the steel head and the polymer-composite rod, contact stresses are removed.

Figure 1 shows the end of a polymer-composite rod;

Fig. 2 shows the connection of the steel head with the polymer-composite body of the pump rod.

The joint consists of a polymer-composite body of the rod 1 and a steel head 2. At the ends of the polymer-composite body of the rod 1, a stepped cylindrical surface З with outer diameters ад, а, д» is turned.

The first stage from the side of the action of the axial load has a diameter and is longer than the others a, d". The end 4 of the polymer-composite rod body is flared to the length Y. On the inner cylindrical surface of the socket of the steel head 2, there are steps 5 of the same profile as the ends of the polymer-composite rod body, the metal insert 8 has an end in the form of a guide cone 7 with a taper angle of 100. ..120"7.

The annular turn 6 is performed on the last stage of the hole of the steel head for filling with glue and placing the loose end of the polymer-composite body of the rod 1 in it. At the same time, the length of the turn Iz should be 5...7 mm less than the length of the cylindrical surface of the insert 8. This ensures the passage of the insert 8 in the hole without jamming during the assembly operation. The fit of the insert 8 and the hole should be with a gap, for free movement of the insert up to the stop.

When assembling the head with the rod, individual fibers of the rod, impregnated with glue, enter the bend b with the help of a guide cone 7, which contributes to the jamming of the end of the rod body in the space of the socket bend under the action of tensile loads on it. To strengthen the connection, epoxy glue is used not only in the place of the ring bend 6, but also over the entire contact surface of the steel head and the rod body. Until the glue hardens, the head with the rod is crimped with a three-stage stamp in several places in the radial direction.

When replacing the worn steel heads, the outer part of the steel head is pre-heated with a high-frequency current. At the same time, the epoxy glue softens, which makes it easier to pull the polymer-composite body of the rod from the steel head. 4 3

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Claims (1)

The method of connecting the steel head with the polymer-composite body of the pump rod, which includes filling the space between the contacting surfaces with an adhesive substance to ensure a fixed connection, which is characterized by the fact that the end of the body of the polymer-composite rod is performed in a stepwise manner by forming cylinders of three diameters in the steel head a corresponding step cylindrical hole is made, while on the last stage of the hole, which has the smallest diameter, a recess is made, an insert with a conical end with a taper angle of 100-120" is inserted into the hole of the head to expand the recess expanded to the length and the end of the polymer-composite impregnated with epoxy glue rod body, which is pressed into the head and crimped in several places together with the steel head with a three-stage stamp.